The present invention relates to an image forming apparatus capable of doing the double-side printing by which the printing is applied to both the front and back surfaces of a recording sheet.
In the related art, various inventions of the image forming apparatus that is capable of doing the double-side printing have been made. Such image forming apparatus applies the desired printing to both the front and back surfaces of one recording sheet respectively. Also, a speedup of the double-side printing (i.e., shortening of a required time for the double-side printing) is demanded in the image forming apparatus that can do the double-side printing.
The related image forming apparatus does the printing on the front surface of one paper, and then does the printing on the back surface of the same paper. Then, when the double-side printing is to be applied to the next paper, the image forming apparatus applies the printing in order to the front surface and the back surface of the second paper. Then, in the conveyance period except a period in which the printing is applied to one paper (the recording sheet) (referred to as a “printing period” hereinafter), the related image forming apparatus conveys the paper at a higher conveyance velocity than the conveyance velocity of the paper during the printing period. Accordingly, the related image forming apparatus can shorten a required time for the double-side printing on one paper, and thus implement the speedup of the double-side printing.
However, the related image forming apparatus can realize the speedup of the double-side printing on one paper, nevertheless such apparatus cannot do the double-side printing on the next paper even after the double-side printing on one paper is completed. That is, this image forming apparatus has room for improvement in shortening of the required period when the double-side printing is applied continuously to plural sheets of paper.
Here, as the system for the double-side printing in the image forming apparatus, there is the system that applies the double-side printing continuously to plural sheets of paper at the same time. Specifically, the image forming apparatus employing this system does the printing on the back surface of the first paper and then does the printing on the back surface of the second paper, and then does the printing in order on the front surface of the first paper and the front surface of the second paper.
The image forming apparatus employing this system conveys the first paper along with the conveyance path such that the printing on the front surface of the first paper can be done while the printing on the back surface of the second paper is applied. That is, both the first paper and the second paper exist simultaneously on the conveyance path of this image forming apparatus. Therefore, when the above-mentioned technology is applied to the image forming apparatus of this system, it is feared that a high-speed feed of one paper in a conveyance period causes a trouble for the printing and the conveyance to the other paper (for example, a collision with the other paper, or the like).
The present invention provides an image forming apparatus for making a high-speed processing possible while keeping a quality of printed results of a double-side printing in a system that the double-side printing is applied continuously at the same time to plural sheets of paper.
To achieve the object of the present invention, the exemplary embodiment of the invention provides an image forming apparatus capable of performing single-side and double-side printing on a recording sheet, comprising:
a conveyance path;
an image forming unit which forms an image on the recording sheet which are passing through the conveyance path;
a fixing unit which fixes the image being formed by the image forming unit on the recording sheet;
a backward conveyance path which guides the recording sheet, in which the image formed on one surface thereof, toward the image forming unit to form the image on the other surface of the recording sheet;
a feeder which feeds the recording sheet at a timing at which a predetermined interval is formed between the plural recording sheets respectively such that the recording sheets are present on the conveyance path and/or the backward conveyance, when a printing is carried out on the recording sheet;
a first conveyance unit which conveys the recording sheet selectively in an eject mode or in a switchback conveyance mode, wherein in the eject mode, the recording sheet on which the image is fixed is ejected to an outside of the apparatus on a downstream side of the fixing unit in a conveyance direction of the recording sheet, and wherein in the switchback conveyance mode, the conveyance direction of the recording sheet in which the image is formed on one surface thereof is switched backward on the downstream side of the fixing unit and then the recording sheet is conveyed toward the backward conveyance path;
a first driver which drives the first conveyance unit;
a second conveyance unit which conveys the recording sheet, which is conveyed by the first conveyance unit in the switchback conveyance mode toward the backward conveyance path, to the image forming unit through the backward conveyance path;
a second driver which drives the second conveyance unit; and
a drive controller which
controls the first driver such that a conveyance velocity at which the recording sheet is conveyed in the switchback conveyance mode is higher than a conveyance velocity at which the recording sheet at which the recording sheet is conveyed in the eject mode, and
controls the first driver such that, in the switchback conveyance mode, the recording sheet is conveyed while lowering the conveyance velocity of the recording sheet in response to a conveyance velocity of the recording sheet conveyed by the second conveyance unit, before the recording sheet reaches the second conveyance unit.